R billeter



July 19, 1955 1 Re. 24,039

RIDGE REIAMER Original Filed Sept. 18, 1950 2 Sheets-Sheet l &

IN V EN TOR.

H. R. BILLETER RIDGE REAMER July 19, 1955 2 Sheets-Sheet. 2

Original Filed Sept. 18, 1950 llir v United States Patent RIDGEREAlVl'ER Henry Robert Billeter, Deerfieid, Ill., assignor to AmmcoTools, Inc., North Chicago, Ill., a corporation of Illinois Original No.2,638,799, dated May 19, 1953, Serial No. 185,396, September 18, 1951Application for reissue August 25, 1954, Serial No. 452,234

8 Claims. (Cl. 77-2) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

This invention relates generally to reamers and has to do particularlywith rearners of the type adapted to remove ring-wear ridges frominternal combustion engine cylinders.

The movement of a piston in a cylinder wears the cylinder wall,increasing the diameter of the cylinder, and since the uppermost pistonring does not reach the top of the cylinder, a ridge is left adjacentthe top of the cylinder wall. In reconditioning cylinders it is oftennecessary to remove this ridge to permit removal of the piston and inall instances removal of the ridge is desirable to insure properfunctioning of the newly installed rings.

Ridge reamers of the type to which the present invention relates areoften provided with resilient means such as a metallic coil spring foryieldingly maintaining the cutting blade in contact with the ridge to bereamed. However it has been found that in cutting certain ridges, forexample those formed in the cylinders of diesel engines, it is necessaryto provide a stiff, high pressure spring to exert the required pressureon the blade. Such a spring renders the reamer unsuitable for cuttingridges which are not so hard.

An object of the present invention therefore is to provide a ridgercamer having a cutting blade so mounted and supported that the reameris adapted for cutting a wide range of ridges of varying hardnessWithout inter fering with the desired action of the blade in cutting theridge in any particular type of cylinder.

Another object is to provide a ridge reamer wherein the cutting blade issupported for sliding and rocking movement in the blade carrier, wherebythe blade is adapted to contact the cylinder ridge suitably to cut awaythe ridge in the desired manner and is at the same time resilientlymaintained in firm cutting engagement with the ridge during the cuttingoperation.

A further object is to provide a ridge rearncr in which the cuttingblade is suitably supported resiliently for engagement with the ridgeand at the some time is substantially prevented from chattering orvibrating during the cutting operation.

Still another object is to provide a ridge reamer having novel means forsupporting and resiliently maintaining the cutting blade in cuttingengagement with the ridge which means is not easily broken or otherwisedamaged in normal use and consequently Will remain fully effective overa long period of use.

A further object is to provide a ridge reamer of very simpleconstruction which is easy and inexpensive to manufacture and assemble,is rugged and not readily damaged and is fully effective in operation.

Another object is to provide a ridge reamer wherein the cutting blade ismovable toward and away from the ridge and maintained in contact withthe ridge by yieldable resilient means which maintains its resiliencythrough the entire range of movement of the blade.

Another object is to provide a ridge reamer of the type having aplurality of cxpansible and contractible Re. 24,039 Reissued July 19,1955 guides adapted to be expanded into contact with the cylinder walls,in which ridge reamer the guides are so arranged that they are capableof a maximum expansion and contraction for any particular size ofreamer, thereby permitting the use of the reamer for reaming cylindersthroughout a wide range of sizes.

A further object is to provide a ridge reamer of the expansible andcontractible type wherein the guides are effectively supported for easyexpansion and contraction and are firmly held in any cutting position,which reamer is formed by a very small number of separate parts therebypermitting the reamer to be manufactured inexpensively and at the sametime minimizing the likelihood of malfunctioning.

Other objects and advantages will be apparent upon reference to thefollowing detailed description and to the accompanying drawings wherein,

Figure l is a side elevational view of the ridge reamer of the presentinvention shown in position in an engine cylinder, the latter beingshown fragmentarily and in section;

Fig. 2 is a top plan view of the ridge reamer;

Fig. 3 is a view from the right of Fig. 1, this figure omittingillustration of the cylinder;

Fig. 4 is a horizontal sectional view taken on line 44 of Fig. 3;

Fig. 5 is a vertical sectional view of the ridge reamer taken on line5-5 of Fig. 4, and showing also fragmcntarily and in section an enginecylinder with the ridge rcamer in position therein;

Pig. 6 is an exploded perspective view of the guide which forms a bladecarrier for the cutting blade, togelher with the cutting blade itselfand the blade equalizer;

Fig. 7 is a perspective view of one of the guides; and

Fig. 8 is a top plan view of the bottom end member making up part of thebody member of the ridge reamer.

Referring now in detail to the drawings, Fig. 1 illustrates the ridgereamer of the present invention as a whole inserted into a cylinder 12of an internal combustion engine such as an automobile engine. Thecylinder wall 14 of the engine, upon long continued movement of thepiston in the cylinder, is worn by the action of the piston rings andbecause the uppermost piston ring does not reach the top of the cylindera ridge such as 16 is formed. The ridge, it will be understood, isillustrated in the drawings in exaggerated condition.

The ridge reamer comprises a body portion 18 which includes a top endmember 26 of generally triangular shape, as viewed in Fig. 2, havingoutwardly extending arms 21 and possessing substantial axial thicknessat its center. The top end member 20 is provided with a polygonal driveshank 22 in the form of a nut adapted for engagement by convenientoperating means for rotating the ridge reamer. The drive shank 22 may besecured in place by imbedding it in the end member 20 in the castingoperation of the latter. The body member 18 also includes a bottom endmember 24 similar in shape to the top end member 20, having outwardlyextending arms 25. The shank 22, as well as top end member 20, are eachprovided with a hole 26 for the reception of an expanding screw 27loosely slidable therein, the lower end 28 of which screw being threadedinto an interiorly threaded hole 29 in the bottom end member 24.

Supporting and guiding members 30, 31 and 32 are slidably mounted ingrooves 34 in the end members 20 and 24, the grooves being disposedtangent to a small base circle concentric with the axis of the device,as seen in Figs. 4 and 8, and extending outwardly in the arms 21 and 25of the top and bottom end members. The supporting and guiding members30, 31 and 32, which will be hereafter referred to as guides forconvenience, include blade-like portions 36. which fit in therespectively aligned grooves 34 in the end members and 24 for slidingmovements of the guides outwardly and inwardly of the body portion. Theblade-like portions 36 and the grooves 34 form effectivetongue-andgroove connections between the body member 18 and the guides30, 31 and 32.. through which rotary motion of the body member istransmitted to the guides.

It will be noted that the sole connection between the and members andthe guides is through the tongue-andgroove connections referred to andthere are no other connections such as guide posts employed in certainprevious types of ridge reamers. Accordingly, a simple and ruggedarticle is produced. Moreover, the elimination of such guide postspermits the guides to be readily arranged in a novel manner ashereinafter described.

The upper and lower edges of the blade-like portions 36 convergeinwardly of the device and the grooves 34- are complementally inclinedto accommodate the inclination of the edges of the blade-like portionsto produce a wcdging effect for forcing the guides 30, 31 and 32outwardly; this operation is accomplished by turning the screw 7.6whereby the screw stem is threaded into the bottom end. member forcingthe latter upwardly relative to the top end member, thereby forcing theguides outwardly. The guides are retained in place by and are retractedinwardly by a surrounding garter spring 38 when the end members arepermitted to move relatively apart.

As mentioned above the guides .30, 3t and 32 extend tangent to a basecircle concentric with the axis of the device and by reason of thisfeature they are enabled to be retracted into the device an extentgreater than would be the case if they were disposed radially. if theywere disposed radially, they would be limited in their inward movementby the screw stem 28 but, because of their tangential relation asreferred to, they are permitted to move in effect in bypassing relationto the screw stem.

Each of the guides and 31 is formed to serve as a guide shoe andaccordingly is provided with a circumferentially offset portion 40adjacent its outer edge and each portion 40 has a smooth radial outersurface 42 engageable with the cylinder wall 14 for guiding the ridgereamer in its operating movements. The portions 40 are provided withgrooves 44 for receiving the garter spring 38, the grooves being ofsufficient depth that the spring does not drag on the cylinder wall. Theouter surface of each portion 40 at its upper end is provided with arecess or cutout portion 46 for accommodating the ridge l6 and each isalso provided with a ledge or overhanging pro jection 43 for engagingthe upper surface of the enginc block for supporting the ridge reamer inthe cylinder.

At least one of the guides is adapted to carry a cutting blade presentlyto be described. The blade carrier guide 32 has a circumferentiallyoffset portion 50 adjacent its radial outer edge generally similar tothe portion 40 of the members 30 and 31 but of greater dimension in adirection circumferentially of the reamer. The portion 50 is providedwith an elongated recess 5.. dispo ed vertically when the ridge reameris in operating position as shown in Fig. l. The recess is substantiallyrectangular in cross section and of substantially greater verticalheight than width. The inner wall of the recess 52 is provided with anaperture 54 for receiving a projection on the blade equalizer to bereferred to later. The side walls of the recess 52 are provided withnotches 56 for receiving the garter spring 38. One of the walls of therecess 52 is cut back at 58 adjacent its upper end. At the upper end ofthe portion 50 is a ledge or overhanging projection 60 serving a purposesimilar to that of the portions 48 and also having a cutout 62 formingan extension of and being in alignment with the recess 52.

A backing up member 64, hereinafter referred to as a blade equalizer, isassociated with the cutting blade for the purpose of resilientlyresisting the inward movement of the cutting blade caused by theresistance to cutting offered by the ridge during rotational operationof ill the reamer, and to urge the cutting blade outwardly after suddeninward thrusts thereof, as well as to progressively urge the cuttingblade outwardly as the ridge is gradually cut away.

The blade equalizer 64 is composed of an elastomer, a name applied tomaterials having certain properties of rubber. Any desired material maybe employed so long as it possesses the desired characteristics andproperties. those characteristics or properties being, resiliency,elasticity, yieldability, distortabiiity, a certain degree of hardness,and freedom from permanent set. The blade equal izer must yield underthe influence of the cutting blade but it must have the necessaryhardness to provide the desired resilient resistance to inward movementof the blade and to urge the cutting blade outwardly, and it must alsobe elastic so that it fully restores to its original shape andcondition. However, the material is of such nature that restoration ofthe blade equalizer to its normal condition is not instantaneous buttakes place after a tem orary delay or, in other words, it takes atemporary set. there being a small time lag in the restoration of thematerial to its normal condition. It is to be noted. however, that thematerial does not take a permanent setv While natural rubber may beemployed it is preferable to employ a synthetic rubber having thedesired properties because of its greater resistance to the deleteriouseifects of oils and greases. Examples of materials which have been foundsuitable are the synthetic material sold by E. l. du Pont de NemoursCompany under the trade name :ieoprene" and that sold by B. F. GoodrichCompany under the trade name "HyCar.

The blade equalizer 64 is of considerably less axial dimension than therecess 52, but of a width only slightly less than the recess, e, g.approximately less in width.

- The rear surface of the blade equalizer indicated at 66 is planar forengaging the wall of the recess, the blade equalizer having a projection68 fitted in the aperture 54 when the blade equalizer is set inposition. The aperture 54 is so positioned that when the blade equuli7eris put in position in the recess. the equalizer is located adjacent theupper portion of the recess as shown clearly in Fig 5, but with itsupper end spaced from the top wall of the recess whereby it is permittedready spreading 01' distortion upwardly. The outer surface it! of theblade equalizer is normally arcuate as shown in Fig. 1. being curvedabout a transverse axis.

The cutting blade assembly 72 is inserted in the recess 52 in engagementwith the blade equalizer. The cutting blade assembly includes a block 74having a groove 76 for receiving the garter spring 38 and a cutoutportion 73 adjacent its upper end and on one side forming a shoulder 80which is disposed substantially radially ol' the reamer. The cuttingblade proper or tip 82 is fitted against the shoulder 80 and permanentlysecured thereto as by brazing. The cutting blade 82 is of the desiredhardness and having the necessary cutting edge for cub ting the ridge 16in the operation of the device. The cutting blade slopes upwardly andoutwardly a slight extent on the order of about one-half of one degree4030) to assure completely cutting the ridge l6 from the cylinder wall.The outer cutting surface of the blade 82 and the surface 84 of theblock together are slightly inclined from a plane perpendicular to therespectiw radius of the device so that the cutting blade presents aclean cutting edge for engaging the ridge 16 upon appropriate rotationof the device clockwise as viewed in Fig. 4. The cutting blade assembly.when titled in the recess 52, is positioned with its upper end in thecutout portion 62 and with its rear surface engaging the: arcuatesurface of the equa izer.

In operation, the ridge reamer in suitably controlled condition isinserted in the cylinder to be reamed with the projections 48 and 60overlying the top rim of the cylinder. The reamer is expanded by turningthe ex panding screw, to urge the guides and blade into en gagement withthe ridge to be reamed. The reamer is properly adjusted in the cylinderand the expanding screw turned to further expand the reamer and thusplace the blade equalizer under the desired compression. The reamer isthen suitably rotated by any suitable tool applied to the drive shank.

As shown in Fig. 5, the cutting blade assembly 74 engages the cylinderwall with the lower end thereof in direct engagement with the cylinderwall below the ridge and the cutting blade in engagement with the ridge16, resulting in the cutting blade assembly sloping downwardly andoutwardly to a slight degree. As the ridge 16 is progressively cut off,the upper end of the cutting blade assembly is urged outwardly under theaction of the blade equalizer until the ridge is finally cut away,whereupon the lower portion of the cutting blade assembly is positionedsubstantially vertically and bears substantially its full length on themain portion of the cylinder wall, while the cutting blade 82 produces aslight outward taper or flare in the upper end of the cylinder wall.This taper is, of course, only slight be cause the inclination of thecutting blade is slight as mentioned above. The cutting blade initiallyengages only the lower portion of the ridge in those cases Where a ridgewas previously cut away leaving a flared surface; upon outward movementof the cutting blade, it progressively cuts away a greater verticalportion of the ridge until it has finally removed the ridge, leaving thetapered or flared portion referred to above.

Because the blade equalizer is positioned in the upper end of therecess, and hence adjacent the upper end of the cutting blade assembly,it bears directly against the end of the blade assembly carrying theblade and is therefore highly effective for urging the cutting blade outwardly into ridge-cutting position.

The arcuate surface 70 of the blade equalizer facilitates theprogressive changes in inclination of the cutting blade assembly 74, i.e., the blade assembly is permitted easy rocking over the arcuatesurface.

Because of the curvature of the surface 70 the cross sectionaldimensions of the blade equalizer are not uniform in a directionlongitudinally of the equalizer and because of this feature the reactionof the equalizer to inward movement of the cutting blade assemblyprogressively increases in proportion to the force urging the cuttingblade assembly inwardly. In the first increment of movement of thecutting blade assembly the blade equalizer is permitted to yield readilybecause the small portion thereof in engagement with the cutting bladeassembly is enabled to spread relatively readily. However, as thecutting blade assembly is moved further inwardly, the blade equalizer isfurther flattened, whereupon thcre is a greater mass of material to bemoved in response to the movement of the cutting blade assembly,resulting in progressively increased resistance to yieldability relativeto unit force applied. By reason of this feature, the cutting blade iseffective for cutting hard cylinders and wide ridges which require morere sistance to inward displacement of the blade in order to cause it tocut away the ridge than softer cylinders or narrower ridges.

As the device is operated and the cutting blade cuts the ridge 16 thereis, of course, a strong force tending to urge the cutting blade assemblyradially inwardly. This force distorts the blade equalizer causing thelatter to spread under the influence thereof, and the equalizer tends torestore to normal, urging the cutting blade assembly outwardly. Theblade equalizer will spread laterally only a slight degree untilconfined against further spreading by the side walls of the recess, butit is permitted to spread longitudinally or vertically to a greatdegree, being permitted to spread vertically at both ends readily. Whena slight force is exerted by the cutting blade assembly against theequalizer the latter is permitted to spread in both transversedirections. Howiii ever, when a greater force is exerted, the bladeequalizer is spread sideways and soon engages the side walls of therecess whereupon it is limited from further spreading in that direction;additional spreading takes place only longitudinally or vertically andsince it can spread only in one transverse direction its effectiveyieldability is lessened and it therefore exerts a greater reaction tothe inward force of the cutting blade assembly. it will thus be seenthat the blade equalizer produces an ellcct similar to the combinedeffect of a weak spring and a strong spring.

t is believed clear that the device of the present invention iseffective for uniformly cutting or reaming a ridge in a cylinder wallregardless of the condition of the various portions of the ridge.

The fact that the material of the blade equalizer 64 takes a slighttemporary set upon compression and does not instantly restore to normalcondition, substantially eliminates chattering of the cutting bladeduring a ridge reaming operation. Contrast is made with previously knowndevices employing such elements as springs for urging the cutting bladeoutwardly into cutting position. Springs and similar devices almostinstantaneously restore to their normal position after being compressed,but in the present invention restoration of the blade equalizer iseffected after only a slight delay. If the cutting blade encounters, forinstance, a hard portion of a ridge and consequently is suddenly forcedinwardly a greater than normal amount, the blade equalizer does notinstantaneously force the blade outwardly but does so after only aslight delay and during this delay the cutting blade will have beenrotated into such a new position that includes a high spot," or theblade equalizer may return the cutting blade outwardly in such mannerthat the cutting blade comes into engagement again with the ridge moregradually, whereby in either case chattering of the blade issubstantially limited.

The material from which the blade equalizer is made permits deformationthereof to take place throughout, and beyond, the range of movement ofthe blade. The resistance of the blade equalizer to deformation, andconsequently to the inward movement of the blade, increases more thanproportionately to the force causing the deformation. Hence, when theblade is expanded outwardly into contact with the ridge to only a slightextent, the equalizer exerts only a slight resistance, but when theblade is expanded outwardly to a greater ex tent, the equalizer exerts aresistance greater in proportion to the greater force tending to movethe blade inwardly.

The characteristics and properties of the rubber-like material of theblade equalizer as set out above, together with its shape and positionin the recess, produce a characteristic yieldablc reaction to the inwardmovement of the cutting blade assembly. In the first portion thereof thereaction of the blade equalizer is substantially in direct proportion tothe unit force applied thereto and in the latter portion the reaction issubstantially increased in proportion to the unit force applied.

It will be noted that there is practically no limit to the yieldabilityof the blade equalizer, regardless of the extent of yielding in aparticular condition, it can yield a greater extent upon the applicationof additional force.

While I have herein shown a preferred embodiment of the invention, it isunderstood that certain changes may be made within the scope of theappended claims.

I claim:

1. A rotatable cylinder ridge reamer comprising top and bottom endmembers movable toward and from each other to expand and contract thereamer, respectivcly, opposing faces of each of said end members havinga plurality of grooves extending tangentially to a base circleconcentric with the axis of rotation of the reamer, means for movingsaid end members toward each other to expand the reamer including amember disposed on the axis of the reamer within the confines of saidbase circle and threadedly engaged with one of said end members andslidable through the other, guide members disposed between and guidinglysupported by said end members. each said guide member having a bodyelement and a head element with the top and bottom edges of said bodyelement converging inwardly away from said head element and slidablymounted in said end member grooves for slide movement inwardly andoutwardly past the axis of the reamer, each said head element extendingcircumferentially from the outer edge of its respective body element tosuch an extent that it moves in a radial plane through said axis as saidbody element is moved inwardly and outwardly of said end member grooves.means for supporting the ridge reamer as a whole for rotation in acylinder to be reamed, a reamer blade assembly carried by one of saidhead elements and adapted to engage the cylinder ridge to be reamed, andmeans yieldably retaining said guide members in said end member groovesand constantly urging said guide members inwardly.

2. A cylinder ridge reamer adapted to be rotated in a cylinder andcomprising opposed top and bottom end members each having at least threesimilarly arranged grooves in their opposing faces extendingtangentially to a base circle concentric with the axis of rotation ofsaid ridge reamer. means including an expansion member extending on saidaxis, within the base circle, and slidably through one of said endmembers and rigidly and adjustably connected to the other of said endmembers for moving said end members toward each other, guide membersextending between said end members, each of said guide members having abody formed with top and bottom edges converging inwardly and slidablein said grooves inwardly and outwardly past said axis as said endmembers are moved toward and away from each other. said grooves beingarranged whereby the medial longitudinal plane of each body intersectsanother of said bodies at a point between the axis and the outer edge ofsaid body, at least one of said bodies having a head parallel to andcircumferentially olfset from the body in position to move in a radialplane passing through said axis as said body is moved inwardly andoutwardly, a cutting blade assembly removably carried in the outer edgeportion of said head. resilient backing means be tween said bladeassembly and said head, and located on both sides of a medial transverseplane through said assembly. and means yieldably urging said guidemembers inwardly.

3. A cylinder ridge reamer adapted to be rotated in a cylinder andcomprising opposed top and bottom end members each having at least threesimilarly arranged grooves in their opposing faces extendingtangentially to a base circle concentric with the axis of rotation ofsaid ridge reamer with the grooves of each end member converginginwardly toward the other cnd member, means in cluding an expansionmember extending on said axis, with in the base circle, and slidablythrough said top end mem her, and rigidly and adjustably connected tosaid bottom end member for moving said end members toward each other,guide members extending between said end members, each of said guidemembers having a body formed with top and bottom edges converginginwardly complementally to said grooves and slidable in said groovesinwardly and outwardly past said axis as said end members are movedtoward and away from each other, said grooves being arranged whereby themedial longitudinal plane of each body intersects another of said bodiesat a point be tween the axis and the outer edge of said body, at leastone of said bodies having a head parallel to and circumferentiallyoflset from the body in position to move in a radial plane passingthrough said axis and said head and formed with an outwardly extendingsupporting projection at its upper end, the outer face of said head andthe lower face of said projection having therein a continuous, elongaterecess, an elongate cutting blade assembly removably carried in saidrecess having a cutting edge on its upper portion, and means yieldablyurging said guide members inwardly.

4. A cylinder ridge reamer adapted to be rotated in a cylinder andcomprising opposed top and bottom end members, means connecting said endmembers for moving them toward each other, a plurality of guide memberscarried between said end members and slidable outwardly with respectthereto upon movement of said guide members toward each other, one ofsaid guide members having an elongate, outwardly opening recess in itsouter surface formed with a generally flat bottom wall, an elongaterubher-like backing member disposed in said recess tapering in thicknessfrom its central portion toward each end and having a generally flatinner surface seated against the bottom wall of the recess, a cuttingblade assembly in said recess and having an elongate body formed with agenerally straight inner edge seated against the outer surface of saidbacking member and a cutting edge along a portion of its outer edge,said backing member being shorter than but not substantially narrowerthan said recess, whereby it is restrained against lateral expansion butfree to expand longitudinally upon compression by said blade assembly,and means yieldably urging said guide members inwardly.

5. A cutting blade and supporting guide assembly for a cylinder ridgereamer, said assembly comprising a guide member having a body formedwith a side edge portion and top and bottom edge portions convergingfrom said side edge portion and a head portion offset laterally fromsaid body adjacent said side edge portion and having an elongate grooveextending longitudinally in the face thereof and substantially in amedial longitudinal plane through said head, an elongate cutting blademember removably disposed in said groove and having a cutting edge onone portion thereof, and resilient backing means disposed in said groovebetween said cutting blade member and the bottom of said groove.

6. A rotatable cylinder ridge reamer comprising top and bottom endmembers, the opposing face of each of said and members having aplurality of groovcs converging inwardly from the outer edge thereof,guide-support members disposed between said end members, each saidguide-support member having a body element and a hcod element with thetop and bottom edges of said body element converging inwardly away fromsaid head element and slidably mounted in said and member grooves forslide movement inwardly and outwardly to contract and t expand thereamer, respectively, said guide-support members comprising the soledrive connection between said end members, means for moving said endmembers toward each other to move said guide-support members outwardlyto expand the reamer, a reamer blade assembly including a radiallymovable blade carried by one of said head elements, and resilient meansacting directly upon said reamcr blade urging said blade outwardlytoward the ridge to be reamed.

7. A rotatable cylinder ridge reamer comprising top and bottom endmembers, the opposing face of each of said end members having aplurality of grooves converging inwardly from the outer edge thereof,guide-supp0rt members disposed between said and members, each saidguide-support member having a body element and a head element with thetop and bottom edges of said body element converging inwardly away fromsaid head element and slidably mounted in said end member grooves forslide movement inwardly and outwardly to contract and expand the reamer,respectively, said guide-support members comprising the sole driveconnection between said end members, means for moving said end memberstoward each other to move said guide-support members outwardly to expandthe reamer including a rigidly-acting rotatable adjusting memberdisposed on the axis of the reamer and threadedly engaged with one ofsaid end members and slidable through the other, means carried by saidguide-support members for supporting the ridge reamer as a whole uponand for r tation in the cylinder to be reamed, a reamer blade assemblycarried by one of said head elements and having a reamer blade portionadapted to engage the cylinder ridge to be reamed and a cylinder wallcontacting portion which together with the other guide-support membersserves to support and guide the reamer rotatively in the cylinder, andresilient means disposed behind and acting directly upon said reamerblade portion and comprising the sole means resiliently urging thereamer blade portion toward the ridge to be reamed, and means yieldablyretaining said guidesupport members in said end member grooves andconstantly urging said guide-support members inwardly.

8. A rotatable cylinder ridge reamer comprising top and bottom endmembers movable toward and from each other, the opposing face of each ofsaid end members having a plurality of grooves converging inwardlytoward the other end member and extending tangentially to a base circleconcentric with the axis of rotation of the reamer, supporting and guidemembers disposed between and supported by said end members, each saidsupporting and guide member having a body element and a head elementwith the top and bottom edges of said body element converging inwardlyaway from said head element and slidably mounted in said end membergrooves for slide movement inwardly and outwardly past the axis of thereamer as said end members are moved toward and from each other, saidsupporting and guiding members comprising the sole driving connectionbetween said end members, means for moving said end members toward eachother to expand the reamer including a member disposed on the axis ofthe reamer within the confines of said base circle and threadedlyengaged with one of said end members and slidable through the other,means carried by said guiding and supporting members for supporting theridge reamer as a whole upon and for rotation in the cylinder to bereamed, a reamer blade carried by one of said head elements and having acutting edge portion adapted to engage the cylinder ridge to be reamedand a guide portion adapted to engage the wall of the cylinder, saidguide portion together with the other of said guiding and supportingmembers rotatably guiding and supporting the reamer in the cylinder,resilient means between said reamer blade and its supporting headelement comprising the sole means urging said cutting edge portion intoengagement with the ridge to be reamed, and means yieldably retainingsaid guide members in said end member grooves and constantly urging saidguide members inwardly.

References Cited in the file of this patent or the original patentUNITED STATES PATENTS 700,825 Ritter, Jr May 27, 1902 1,491,621 Pfanderet al. Apr. 22, 1924 1,980,288 Olson Nov. 13, 1934 2,637,224 MitchellMay 5, 1953

